What does "terminate called after throwing an instance of 'std::out_of_range'" mean?

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This error message means that the program has attempted to access a value outside the range of valid indices or values of a specific data type. The program has thrown an instance of the 'std::outofrange' class to indicate that this error has occurred. The 'terminate' function is called by the program to indicate that it cannot continue executing due to an unrecoverable error.